Semiconductor device and manufacturing method thereof

ABSTRACT

The semiconductor device includes a semiconductor element having an electrode formed on a surface thereof, and a metal wiring formed on the surface of the semiconductor element and electrically connected to the electrode. The metal wiring has an external electrode portion functioning as an external electrode. A thickness of the external electrode portion is greater than that of a non-electrode portion of the metal wiring, i.e., a portion of the metal wiring other than the external electrode portion.

BACKGROUND OF THE INVENTION

[0001] The present invention generally relates to a semiconductor devicein which a metal wiring is formed so as to be electrically connected toan electrode of a semiconductor element and a part of the metal wiringis used as an external electrode, and a manufacturing method of thesame. More particularly, the present invention relates to asemiconductor device having excellent junction reliability between ametal wiring and a ball electrode mounted to an external electrodeportion of the metal wiring, and a manufacturing method of the same.

[0002] With recent reduction in size and improvement in functions ofelectronic equipments, an increasing number of input/output (I/O) pinsis formed in a semiconductor element, and therefore the pitch ofelectrodes is reduced.

[0003] Especially in a CSP (Chip Size Package) type semiconductordevice, electrodes of a semiconductor element are formed by a dryetching method in a diffusion process, whereas wiring electrodes of asubstrate on which the semiconductor element is mounted are formed by awet etching method in an assembling process. Accordingly, the pitch ofthe wiring electrodes of the substrate on which the semiconductorelement is mounted is necessarily greater than that of the electrodes ofthe semiconductor element. In view of this, a semiconductor device isincreasingly developed which deals with the difference between theelectrode pitch of the semiconductor element and the wiring-electrodepitch of the substrate. In such a semiconductor device, metal wiringsare formed so as to be electrically connected to the respectiveelectrodes of the semiconductor element and a part of each metal wiringis used as an external electrode in order to increase the distancebetween the external electrodes.

[0004] Hereinafter, a conventional semiconductor device will bedescribed with reference to the figures.

[0005]FIG. 15A is a perspective plan view of the conventionalsemiconductor device. FIG. 15B shows an example of the cross-sectionalstructure taken along line XV-XV of FIG. 15A. FIG. 15C shows anotherexample of the cross-sectional structure taken along line XV-XV of FIG.15A.

[0006] As shown in FIGS. 15A and 15B, electrodes 2 are formed on thesurface of a semiconductor element 1. A passivation film 3 is formedover the surface of the semiconductor element 1. The passivation film 3is formed from silicon nitride (SiN) or the like, and has an opening oneach electrode 2. Metal wirings 4 are formed on the passivation film 3.Each metal wiring 4 is formed from copper (Cu) and electricallyconnected to a corresponding one of the electrodes 2. A solder resistfilm 5 is formed on the metal wirings 4 and the passivation film 3. Thesolder resist film 5 has an opening on a portion of each metal wiring 4which functions as an external electrode (hereinafter, referred to as“external electrode portion”). In order to electrically connect theelectrodes 2 formed on the surface of the semiconductor element 1 towiring electrodes of a substrate (not shown) on which the semiconductorelement 1 is mounted, respectively, a ball electrode 6 formed fromsolder is connected in a molten state to each opening of the solderresist film 3, that is, to the external electrode portion of each metalwiring 4.

[0007] As shown in FIG. 15C, an insulating resin layer 7 may be formedbetween the semiconductor element 1 having the passivation film 3thereon and the metal wirings 4.

[0008] In each of the forms of the conventional semiconductor devicedescribed above, the wiring electrodes of the substrate on which thesemiconductor device is mounted are respectively connected to the metalwirings 4 of Cu formed on the surface of the semiconductor element 1through the ball electrodes 6 formed from solder. In other words, whenthe metal wirings 4 are formed from Cu (which is a commonly used metalwiring material), metal junction of Cu (the metal wirings 4) and solder(the ball electrodes 6) is formed at the boundary between the metalwiring 4 and the ball electrode 6.

[0009] In the above conventional semiconductor device, however, tin (Sn)contained in solder of the ball electrode 6 diffuses into Cu of themetal wiring 4 to form a Sn—Cu alloy layer. As a result, in the portionof the metal wiring 4 on which the ball electrode 6 is mounted (i.e.,the external electrode portion) and the portion near the externalelectrode portion, the Sn—Cu alloy grows in the most part of the metalwiring 4. The Sn—Cu alloy is weak and hard. The semiconductor device 1,the resin film covering the surface of the semiconductor element 1 andthe substrate have different thermal expansion coefficients.Accordingly, when the temperature is varied to melt the ball electrodesin the process of mounting the semiconductor device onto the substrate,stresses are generated due to such a difference in thermal expansioncoefficient. Accordingly, the Cu—Sn alloy layer formed in the portion ofthe metal wiring 4 to which the ball electrode 6 is mounted is likely tobe broken by the stresses.

SUMMARY OF THE INVENTION

[0010] In view of the above problems, it is an object of the presentinvention to provide a semiconductor device having a metal wiringelectrically connected to an electrode of a semiconductor element, andhaving improved junction reliability between the metal wiring and a ballelectrode mounted on an external electrode portion of the metal wiring.

[0011] According to one aspect of the present invention, a semiconductordevice includes a semiconductor element having an electrode formed on asurface thereof, and a metal wiring formed on the surface of thesemiconductor element and electrically connected to the electrode. Themetal wiring has an external electrode portion functioning as anexternal electrode. A thickness of the external electrode portion isgreater than that of a non-electrode portion of the metal wiring, i.e.,a portion of the metal wiring other than the external electrode portion.

[0012] According to the above semiconductor device, in the metal wiringelectrically connected to the electrode of the semiconductor element,the thickness of the external electrode portion is greater than that ofthe non-electrode portion. The external electrode portion of the metalwiring and a wiring electrode of a substrate on which the semiconductordevice is mounted may be connected to each other by a ball electrodeformed from solder. In this case, when the metal wiring contain, e.g.,Cu (which is a commonly used metal wiring material), Sn contained insolder of the ball electrode diffuses into Cu contained in the metalwiring, whereby a Sn—Cu alloy layer having low strength grows in thethickness direction of the external electrode portion. However, sincethe thickness of the external electrode portion of the metal wiring isgreater than that of the non-electrode portion of the metal wiring, thisSn—Cu alloy layer can be prevented from growing through the entirethickness of the external electrode portion. In other words, it isensured that the thickness of the low-strength Sn—Cu alloy layer in theexternal electrode portion of the metal wiring is smaller than thethickness of the external electrode portion. Since a part of theexternal electrode portion is left unchanged into the Sn—Cu alloy layer,the strength of the metal wiring can be maintained even if Cu is used asa metal wiring material. The semiconductor element, the resin filmcovering the surface of the semiconductor element, and the substratehave different thermal expansion coefficients. Therefore, when thetemperature is varied in the process of hardening the resin filmcovering the surface of the semiconductor element or the process ofmounting the semiconductor device onto the substrate, stresses aregenerated due to such a difference in thermal expansion coefficient.However, the above structure can prevent disconnection of the metalwiring even if such stresses are generated.

[0013] According to the above semiconductor device, the thickness of thenon-electrode portion of the metal wiring is smaller than that of theexternal electrode portion to which the ball electrode is mounted. Themetal wiring having a small thickness facilitates formation of finewirings by etching. As a result, the width of the metal wiring or thepitch of the metal wirings can be reduced, enabling reduction in size ofthe semiconductor device.

[0014] Preferably, the semiconductor device further includes aninsulating film formed on the metal wiring and the surface of thesemiconductor element, and having an opening exposing the externalelectrode portion. An exposed surface of the external electrode portionis preferably flush with or higher than a surface of the insulatingfilm.

[0015] This prevents a wiring or electrode of a substrate on which thesemiconductor device is mounted from contacting the non-electrodeportion of the metal wiring of the semiconductor device. Moreover, theexposed surface of the external electrode portion is flush with orhigher than the surface of the insulating film. Therefore, the ballelectrode can be mounted to the external electrode portion withoutproducing a gap therebetween. As a result, sufficient junction betweenthe ball electrode and the external electrode portion can be ensured.When the exposed surface of the external electrode portion is higherthan the surface of the insulating film, a substantial thickness of ametal portion of the external electrode portion is increased. Therefore,the following effects can be obtained: when Sn contained in solder ofthe ball electrode diffuses into Cu contained in the metal wiring, aSn—Cu alloy layer having low strength grows in the thickness directionof the external electrode portion. As described above, however, sincethe substantial thickness of the metal portion of the external electrodeportion is increased, it is ensured that a greater part of the externalelectrode portion is left unchanged into the Sn—Cu alloy in thethickness direction of the external electrode portion. When thetemperature is varied in a process such as the process of mounting thesemiconductor device onto the substrate, stresses are generated due tothe difference in thermal expansion coefficient between thesemiconductor device and the substrate. However, the above structure canmore reliably prevent disconnection of the metal wiring even if suchstresses are generated. Note that, when the exposed surface of theexternal electrode portion is higher than the surface of the insulatingfilm, the external electrode portion may be bonded to the wiringelectrode of the substrate by solder without using the ball electrode.In this case, the same effects as those described above can be obtained.

[0016] Preferably, the metal wiring is formed from a metal containingcopper.

[0017] This enables reduction in resistance of the metal wiring.

[0018] Preferably, the above semiconductor device further includes aninsulating resin layer formed between the surface of the semiconductorelement and the metal wiring. The metal wiring is preferably formedalong a surface of the insulating resin layer.

[0019] When the temperature is varied to melt the ball electrode in theprocess of mounting the semiconductor device to the substrate, stressesare generated due to the difference in thermal expansion coefficientbetween the semiconductor device and the substrate. However, thesestresses can be absorbed by the insulating resin layer. As a result, thestresses are reduced, whereby the external electrode portion of themetal wiring to which the ball electrode is connected can be preventedfrom being broken by the stresses.

[0020] Preferably, the thickness of the external electrode portion is ina range of 10 μm to 20 μm.

[0021] In this case, the metal wiring can be reliably prevented frombeing disconnected at the external electrode portion, and patterndeformation generated in the process of forming the external electrodeportion having a greater thickness by etching can be suppressed.

[0022] According to another aspect of the present invention, a methodfor manufacturing a semiconductor device includes: a first step offorming, on a surface of a semiconductor element having an electrodeformed thereon, a metal wiring electrically connected to the electrode;a second step of forming, on the surface of the semiconductor elementand the metal wiring, an insulating film having an opening which exposesa region of the metal wiring layer where an external electrode is to beformed; and a third step of forming a metal-material embedded portion inthe opening so that a surface of the metal-material embedded portion isflush with or higher than a surface of the insulating film.

[0023] According to the above manufacturing method, the metal wiring isformed so as to be electrically connected to the electrode of thesemiconductor element. The insulating film is then formed so as to havean opening which exposes the region of the metal wiring where anexternal electrode is to be formed. Thereafter, the metal-materialembedded portion is embedded in the opening so that the surface of themetal-material embedded portion is flush with or higher than the surfaceof the insulating film. As a result, the thickness of the externalelectrode portion (i.e., the total thickness of the metal-materialembedded portion embedded in the opening and the metal wiring locatedunder the metal-material embedded portion) is greater than the thicknessof a non-electrode portion of the metal wiring, that is, the portion ofthe metal wiring other than the external electrode portion. Accordingly,the same effects as those of the semiconductor device of the presentinvention can be obtained.

[0024] According to the above manufacturing method, the non-electrodeportion of the metal wiring (i.e., the portion of the metal wiring otherthan the external electrode portion) is covered with the insulatingfilm. This prevents a wiring or electrode of a substrate on which thesemiconductor device is mounted from contacting the non-electrodeportion of the metal wiring of the semiconductor device. Moreover, thesurface of the metal-material embedded portion, that is, the exposedsurface of the external electrode portion, is flush with or higher thanthe surface of the insulating film. Therefore, a ball electrode can bemounted to the external electrode portion without producing a gaptherebetween. As a result, sufficient junction between the ballelectrode and the external electrode portion can be ensured. When theexposed surface of the external electrode portion is higher than thesurface of the insulating film, a substantial thickness of a metalportion of the external electrode portion is increased. Therefore, thefollowing effects can be obtained: when Sn contained in solder of theball electrode diffuses into Cu contained in the metal wiring, a Sn—Cualloy layer having low strength grows in the thickness direction of theexternal electrode portion. As described above, however, since thesubstantial thickness of the metal portion of the external electrodeportion is increased, it is ensured that a greater part of the externalelectrode portion is left unchanged into the Sn—Cu alloy in thethickness direction of the external electrode portion. When thetemperature is varied in a process such as the process of mounting thesemiconductor device onto the substrate, stresses are generated due tothe difference in thermal expansion coefficient between thesemiconductor device and the substrate. However, the above structure canmore reliably prevent disconnection of the metal wiring even if suchstresses are generated. Note that, when the exposed surface of theexternal electrode portion (i.e., the surface of the metal-materialembedded portion) is higher than the surface of the insulating film, theexternal electrode portion may be bonded to the wiring electrode of thesubstrate by solder without using the ball electrode. In this case, thesame effects as those described above can be obtained.

[0025] Preferably, the above manufacturing method further includes,before the first step, the step of forming an insulating resin film onthe surface of the semiconductor element except the electrode. The firststep preferably includes the step of forming the metal wiring along asurface of the insulating resin layer.

[0026] When the temperature is varied to melt a ball electrode in theprocess of mounting the semiconductor device to the substrate, stressesare generated due to the difference in thermal expansion coefficientbetween the semiconductor device and the substrate. According to theabove manufacturing method, however, these stresses can be absorbed bythe insulating resin layer. As a result, the stresses are reduced,whereby the external electrode portion of the metal wiring to which theball electrode is connected can be prevented from being broken by thestresses.

[0027] In the above manufacturing method, the third step may include thestep of forming a metal film on the insulating film so as to completelyfill the opening, forming a mask pattern which covers a region of themetal film located on the opening, removing a region of the metal filmlocated outside the mask pattern, and removing the mask pattern.

[0028] In the above manufacturing method, the third step may include thestep of forming a first metal film on the surface of the insulating filmso as to partially fill the opening, forming a mask pattern which coversa region of the first metal film located outside the opening, forming asecond metal film on a region of the first metal film located in theopening, and removing the mask pattern and the region of the first metalfilm located outside the opening.

[0029] In the above manufacturing method, the semiconductor element maybe provided in each of a plurality of chip regions of a semiconductorwafer, which are defined by a dicing line. The method may furtherinclude, after the third step, the step of dicing the semiconductorwafer along the dicing line by a rotating blade in order to divide thesemiconductor wafer into chips of the semiconductor elements.

[0030] According to still another aspect of the present invention, amethod for manufacturing a semiconductor device includes: a first stepof forming, on a surface of a semiconductor element having an electrodeformed thereon, a metal wiring electrically connected to the electrode;a second step of forming a projecting electrode on a region of the metalwiring where an external electrode is to be formed; and a third step offorming an insulating film on the surface of the semiconductor elementand the metal wiring so as to expose at least a top portion of theprojecting electrode.

[0031] According to the above manufacturing method, the metal wiring isformed so as to be electrically connected to the electrode of thesemiconductor element. The projecting electrode is then formed on theregion of the metal wiring where an external electrode is to be formed.Thereafter, the insulating film is formed so as to expose at least thetop portion of the projecting electrode. As a result, the thickness ofthe external electrode portion (i.e., the total thickness of theprojecting electrode and the metal wiring located thereunder) is greaterthan the thickness of a non-electrode portion of the metal wiring, thatis, the portion of the metal wiring other than the external electrodeportion. Accordingly, the same effects as those of the semiconductordevice of the present invention can be obtained.

[0032] According to the above manufacturing method, the non-electrodeportion of the metal wiring (i.e., the portion of the metal wiring otherthan the external electrode portion) is covered with the insulatingfilm. This prevents a wiring or electrode of a substrate on which thesemiconductor device is mounted from contacting the non-electrodeportion of the metal wiring of the semiconductor device. Moreover, thesurface of the top portion of the projecting electrode, that is, theexposed surface of the external electrode portion, is higher than thesurface of the insulating film. Therefore, a ball electrode can bemounted to the external electrode portion without producing a gaptherebetween. As a result, sufficient junction between the ballelectrode and the external electrode portion can be ensured. Moreover,since the exposed surface of the external electrode portion is higherthan the surface of the insulating film, a substantial thickness of ametal portion of the external electrode portion is increased. Therefore,the following effects can be obtained: when Sn contained in solder ofthe ball electrode diffuses into Cu contained in the metal wiring, aSn—Cu alloy layer having low strength grows in the thickness directionof the external electrode portion. As described above, however, sincethe substantial thickness of the metal portion of the external electrodeportion is increased, it is ensured that a greater part of the externalelectrode portion is left unchanged into the Sn—Cu alloy in thethickness direction of the external electrode portion. When thetemperature is varied in a process such as the process of mounting thesemiconductor device onto the substrate, stresses are generated due tothe difference in thermal expansion coefficient between thesemiconductor device and the substrate. However, the above structure canmore reliably prevent disconnection of the metal wiring even if suchstresses are generated. Note that, when the exposed surface of theexternal electrode portion (i.e., the top portion of the projectingelectrode) is higher than the surface of the insulating film, theexternal electrode portion may be bonded to the wiring electrode of thesubstrate by solder without using the ball electrode. In this case, thesame effects as those described above can be obtained.

[0033] Preferably, the above manufacturing method further includes,before the first step, the step of forming an insulating resin film onthe surface of the semiconductor element except the electrode. The firststep preferably includes the step of forming the metal wiring along asurface of the insulating resin layer.

[0034] When the temperature is varied to melt a ball electrode in theprocess of mounting the semiconductor device to the substrate, stressesare generated due to the difference in thermal expansion coefficientbetween the semiconductor device and the substrate. According to theabove manufacturing method, however, these stresses can be absorbed bythe insulating resin layer. As a result, the stresses are reduced,whereby the external electrode portion of the metal wiring to which theball electrode is connected can be prevented from being broken by thestresses.

[0035] In the above manufacturing method, the semiconductor element maybe provided in each of a plurality of chip regions of a semiconductorwafer, which are defined by a dicing line. The above manufacturingmethod may further includes, after the third step, the step of dicingthe semiconductor wafer along the dicing line by a rotating blade inorder to divide the semiconductor wafer into chips of the semiconductorelements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is a cross-sectional view of a semiconductor deviceaccording to a first embodiment of the present invention;

[0037]FIG. 2 is a cross-sectional view of the semiconductor deviceaccording to the first embodiment of the present invention;

[0038]FIG. 3 is a cross-sectional view of a semiconductor deviceaccording to a modification of the first embodiment of the presentinvention;

[0039]FIG. 4 is a cross-sectional view of a semiconductor deviceaccording to a second embodiment of the present invention;

[0040]FIG. 5 is a cross-sectional view of the semiconductor deviceaccording to the second embodiment of the present invention;

[0041]FIG. 6 is a cross-sectional view of a semiconductor deviceaccording to a modification of the second embodiment of the presentinvention;

[0042]FIGS. 7A, 7B, 7C, 7D and 7E illustrate the steps of a method formanufacturing a semiconductor device according to a third embodiment ofthe present invention;

[0043]FIGS. 8A and 8B illustrate the steps of the method formanufacturing a semiconductor device according to the third embodimentof the present invention;

[0044]FIGS. 9A, 9B, 9C and 9D illustrate the steps of a method formanufacturing a semiconductor device according to a fourth embodiment ofthe present invention;

[0045]FIGS. 10A, 10B and 10C illustrate the steps of the method formanufacturing a semiconductor device according to the fourth embodimentof the present invention;

[0046]FIGS. 11A, 11B, 11C, 11D and 11E illustrate the steps of a methodfor manufacturing a semiconductor device according to a fifth embodimentof the present invention;

[0047]FIGS. 12A, 12B and 12C illustrate the steps of the method formanufacturing a semiconductor device according to the fifth embodimentof the present invention;

[0048]FIGS. 13A, 13B, 13C and 13D illustrate the steps of a method formanufacturing a semiconductor device according to a sixth embodiment ofthe present invention;

[0049]FIGS. 14A and 14B illustrate the steps of the method formanufacturing a semiconductor device according to the sixth embodimentof the present invention; and

[0050]FIG. 15A is a perspective plan view of a conventionalsemiconductor device, FIG. 15B shows an example of the cross-sectionalstructure taken along line XV-XV of FIG. 15A, and FIG. 15C shows anotherexample of the cross-sectional structure taken along line XV-XV of FIG.15A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] (First Embodiment)

[0052] Hereinafter, a semiconductor device according to the firstembodiment of the present invention will be described with reference tothe figures.

[0053]FIGS. 1 and 2 are cross-sectional views of the semiconductordevice of the first embodiment.

[0054] As shown in FIG. 1, electrodes 12 are formed on the surface of asemiconductor element 11. A passivation film 13 is formed over thesurface of the semiconductor element 11. The passivation film 13 isformed from, e.g., SiN, and has an opening on each electrode 12. Thepassivation film 13 protects the surface of the semiconductor element11. Metal wirings 14 containing, e.g., Cu are formed on the passivationfilm 13. Each metal wiring 14 is electrically connected to acorresponding one of the electrodes 12. An insulating film 15 is formedon the metal wirings 14 and the passivation film 13. The insulating film15 has openings in order to expose a portion of each metal wiring 14which functions as an external electrode (hereinafter, referred to as“external electrode portion 14 a”). For example, the insulating film 15is a resin film formed from solder resist or the like. As shown in FIG.2, in order to electrically connect the electrodes 12 formed on thesurface of the semiconductor element 11 to wiring electrodes of asubstrate (not shown) on which the semiconductor element 11 is mounted,ball electrodes 16, which are formed from solder, are connected in amolten state to the openings of the insulating film 15, that is, theexternal electrode portions 14 a of the metal wirings 14, respectively.The electrodes 12 of the semiconductor element 11 and the wiringelectrodes of the substrate are thus respectively connected to eachother through the metal wirings 14 and the ball electrodes 16.

[0055] The present embodiment is characterized in that the thickness(e.g., 14 μm) of the external electrode portion 14 a of the metal wiring14 is greater than that of the other portion of the metal wiring 14(hereinafter, referred to as “non-electrode portion”). For example, suchexternal electrode portions 14 a having a greater thickness is formed bythe following method: first, the insulating film 15 is formed. Openingsare formed in the insulating film 15 at positions where the ballelectrodes 16 are to be mounted on the Cu-containing metal wirings 14,respectively. Thereafter, the openings are filled with a metal material(more specifically, Cu). The external electrode portions 14 a having agreater thickness are thus formed. In this case, the thickness of theexternal electrode portion 14 a is equal to the total thickness of themetal wiring 14 and the portion filled with the metal material(hereinafter, referred to as “metal-material embedded portion”).

[0056] According to the first embodiment, in each metal wiring 14electrically connected to a corresponding one of the electrodes 12, thethickness of the external electrode portion 14 a is greater than that ofthe non-electrode portion. The external electrode portions 14 a and thewiring electrodes of the substrate on which the semiconductor device ismounted are respectively connected to each other by the ball electrodes16. When the metal wirings 14 contain, e.g., Cu (which is a commonlyused metal wiring material), Sn contained in solder of the ballelectrode 16 diffuses into Cu contained in the metal wiring 14, wherebya Sn—Cu alloy layer having low strength grows in the thickness directionof the external electrode portion 14 a. However, since the thickness ofthe external electrode portion 14 a of the metal wiring 14 is greaterthan that of the non-electrode portion of the metal wiring 14, thisSn—Cu alloy layer can be prevented from growing through the entirethickness of the external electrode portion 14 a. In other words, it isensured that the thickness of the Sn—Cu alloy layer in the externalelectrode portion 14 a is smaller than the thickness of the externalelectrode portion 14 a. Since a part of the external electrode portion14 a is left unchanged into the Sn—Cu alloy layer, the strength of themetal wiring 14 can be maintained even if Cu is used as a metal wiringmaterial. The semiconductor element 11, the resin film covering thesurface of the semiconductor element 11, and the substrate havedifferent thermal expansion coefficients. Therefore, when thetemperature is varied in the process of hardening the resin filmcovering the surface of the semiconductor element 11 or the process ofmounting the semiconductor device onto the substrate, stresses aregenerated due to such a difference in thermal expansion coefficient.Even if such stresses are generated, however, the above structure of thefirst embodiment can prevent the Sn—Cu alloy layer having low strengthfrom being broken and thus can prevent disconnection of the metalwirings 14.

[0057] More specifically, in the first embodiment, the thickness of thenon-electrode portion of the metal wiring 14 is preferably in the rangeof 0.01 μm to 8 μm, and more preferably in the range of 0.01 μm to 4 μm.The reason for this is as follows: if the thickness of the metal wiring14 is less than 0.01 μm, the strength of the metal wiring 14 is reduced,causing disconnection and the like. If the thickness of the metal wiring14 is greater than 8 μm, it is difficult to etch the metal film forforming the metal wirings 14. This makes it difficult to reduce the sizeof the wiring pattern of the metal wirings 14.

[0058] In the first embodiment, the thickness of the external electrodeportion 14 a of the metal wiring 14 (e.g., the total thickness of thenon-electrode portion of the metal wiring 14 and the metal-materialembedded portion) is preferably in the range of 10 μm to 20 μm. Thereason for this is as follows: the inventors fabricated a plurality ofsemiconductor device samples so that the external electrode portion 14 aof each metal wiring 14 has a greater thickness than the non-electrodeportion of the metal wiring 14. Such external electrode portions 14 awere formed by forming the metal-material embedded portion in eachopening of the insulating film 15 (i.e., on each region where anexternal electrode is to be formed; hereinafter, referred to as“external-electrode formation region”). In these semiconductor devicesamples, the thickness of the external electrode portion 14 a was 5 μm,7 μm, 9 μm and 11 μm, respectively. After each semiconductor devicesample was mounted on a substrate, a temperature cycle test (environmentreliability test) was conducted in order to determine whether or noteach semiconductor device sample is capable of preventing disconnectionof the metal wirings 14. In the temperature cycle test, eachsemiconductor device sample mounted on the substrate was repeatedlysubjected to the temperatures of −40° C. and 80° C. In thisexperimentation, 1,000 cycles were conducted in the temperature cycletest. In each cycle, the temperature was varied from −40° C. to 80° C.and then reduced back to −40° C. The following result was obtained bythe temperature cycle test: when the thickness of the external electrodeportion 14 a (the total thickness of the metal wiring 14 and themetal-material embedded portion) is 5 μm, the metal wiring 14 wasdisconnected at 50 cycles. For 7 μm, the metal wiring 14 wasdisconnected at 200 cycles. For 9 μm, the metal wiring 14 wasdisconnected at 700 cycles. For 11 μm, the metal wiring 14 was notdisconnected. The above experimentation result shows that the thickerthe external electrode portion 14 a is, the less the metal wiring 14 islikely to be disconnected. More specifically, the metal wiring 14 isless likely to be disconnected when the thickness of the externalelectrode portion 14 a is about 10 μm or more. Note that the externalelectrode portion 14 a having a greater thickness than the non-electrodeportion of the metal wiring 14 is herein formed using the metal-materialembedded portion. In this case, if the thickness of the externalelectrode portion 14 a exceeds 20 μm, greater pattern deformation wouldbe generated in the process of forming the metal-material fillingportion by a wet etching method.

[0059] According to the first embodiment, the portion of the metalwiring 14 other than the external electrode portion 14 a (i.e., thenon-electrode portion of the metal wiring 14) is covered with theinsulating film 15. This prevents wirings or electrodes of the substrateon which the semiconductor device is mounted from contacting thenon-electrode portions of the metal wirings 14 of the semiconductordevice. It is preferable that the exposed surface of the externalelectrode portion 14 a is flush with or higher than the surface of theinsulating film 15 (in the specification, the term “flush” also includes“approximately flush”). In other words, it is preferable that thethickness of the external electrode portion 14 a is equal to or greaterthan that of the insulating film 15 (in the specification, the term“equal” also includes “approximately equal”). The reason for this is asfollows: if the external electrode portion 14 a is thinner than theinsulating film 15, the ball electrode 16 cannot be mounted to theexternal electrode portion 14 a (that is, the opening of the insulatingfilm 15) without producing a gap therebetween. As a result, sufficientjunction between the ball electrode 16 and the external electrodeportion 14 a cannot be ensured.

[0060] Note that, in the first embodiment, the material of the metalwirings 14 is not specifically limited. For example, a material mainlycontaining Cu, titanium (Ti), tungsten (W), chromium (Cr), aluminum (Al)or the like may be used. Alternatively, another conductive metalmaterial may be used. However, forming the metal wiring 14 from aCu-containing metal enables reduction in resistance of the metal wiring14.

[0061] (Modification of First Embodiment)

[0062] Hereinafter, a semiconductor device according to a modificationof the first embodiment will be described with reference to the figures.

[0063]FIG. 3 is a cross-sectional view of the semiconductor deviceaccording to the modification of the first embodiment. Note that, in themodification of the first embodiment, the same elements as those of thesemiconductor device of the first embodiment in FIG. 1 are denoted withthe same reference numerals and characters, and description thereof isomitted.

[0064] As shown in FIG. 3, electrodes 12 are formed on the surface of asemiconductor element 11. A passivation film 13 is formed over thesurface of the semiconductor element 11. The passivation film 13 has anopening on each electrode 12. Metal wirings 14 are formed on thepassivation film 13. Each metal wiring 14 is electrically connected to acorresponding one of the electrodes 12. An insulating film 15 is formedon the metal wirings 14 and the passivation film 13. The insulating film15 has openings in order to expose a portion of each metal wiring 14which functions as an external electrode (hereinafter, referred to as“external electrode portion 14 b”).

[0065] The modification of the first embodiment is different from thefirst embodiment in that each external electrode portion 14 b has amushroom-like projection over a corresponding one of the openings of theinsulating film 15. The mushroom-like projection is larger than theopening of the insulating film 15. Therefore, the exposed surface of theexternal electrode portion 14 b is higher than the surface of theinsulating film 15. As a result, a substantial thickness of a metalportion of the external electrode portion 14 b is larger than that ofthe external electrode portion 14 a of the first embodiment in FIG. 1.Therefore, the following effects can be obtained: when the externalelectrode portions 14 b and wiring electrodes of a substrate on whichthe semiconductor device is mounted are respectively connected to eachother by ball electrodes formed from solder, Sn contained in solder ofthe ball electrode diffuses into Cu contained in the metal wiring 14. Asa result, a Sn—Cu alloy layer having low strength grows in the thicknessdirection of the external electrode portion 14 b. As described above,however, the substantial thickness of the metal portion of the externalelectrode portion 14 b is larger than that of the external electrodeportion 14 a of the first embodiment in FIG. 1. It is therefore ensuredthat a greater part of the external electrode portion 14 b is leftunchanged into the Sn—Cu alloy in the thickness direction of theexternal electrode portion 14 b. When the temperature is varied in aprocess such as the process of mounting the semiconductor device ontothe substrate, stresses are generated due to the difference in thermalexpansion coefficient between the semiconductor device and thesubstrate. However, the above structure of the modification of the firstembodiment can more reliably prevent disconnection of the metal wirings14 even if such stresses are generated.

[0066] Note that, in the modification of the first embodiment, theexternal electrode portions 14 b may be bonded to the wiring electrodesof the substrate by solder without using the ball electrodes. In thiscase, the same effects as those described above can be obtained.

[0067] (Second Embodiment)

[0068] Hereinafter, a semiconductor device according to the secondembodiment of the present invention will be described with reference tothe figures.

[0069]FIGS. 4 and 5 are cross-sectional views of the semiconductordevice of the second embodiment. Note that, in the second embodiment,the same elements as those of the semiconductor device of the firstembodiment in FIG. 1 are denoted with the same reference numerals andcharacters, and description thereof is partly omitted.

[0070] As shown in FIG. 4, electrodes 12 are formed on the surface of asemiconductor element 11. A passivation film 13 is formed over thesurface of the semiconductor element 11. The passivation film 13 has anopening on each electrode 12. An insulating resin layer 17 is formed onthe passivation film 13 excluding the regions near the electrodes 12.For example, the insulating resin layer 17 is formed from an epoxy resinhaving low elasticity. Metal wirings 14 are formed along the surface ofthe insulating resin layer 17. Each metal wiring 14 is electricallyconnected to a corresponding one of the electrodes 12. An insulatingfilm 15 is formed on the metal wirings 14, the insulating resin layer 17and the passivation film 13. The insulating film 15 has openings inorder to expose a portion of each metal wiring 14 which functions as anexternal electrode (hereinafter, referred to as “external electrodeportion 14 a”). For example, the insulating film 15 is a resin filmformed from solder resist or the like. As shown in FIG. 5, in order toelectrically connect the electrodes 12 formed on the surface of thesemiconductor element 11 to wiring electrodes of a substrate (not shown)on which the semiconductor element 11 is mounted, ball electrodes 16,which are formed from solder, are connected in a molten state to theopenings of the insulating film 15, that is, the external electrodeportions 14 a of the metal wirings 14, respectively. The electrodes 12of the semiconductor element 11 and the wiring electrodes of thesubstrate are thus respectively connected to each other through themetal wirings 14 and the ball electrodes 16.

[0071] A first characteristic of the second embodiment is that, like thefirst embodiment, the thickness of the external electrode portion 14 aof the metal wiring 14 is greater than that of the other portion of themetal wiring 14 (i.e., the non-electrode portion).

[0072] A second characteristic of the second embodiment is that, asdescried above, the insulating resin layer 17, which is formed from anepoxy resin having low elasticity or the like, is formed between themetal wirings 14 each electrically connected to a corresponding one ofthe electrodes 12 of the semiconductor element 11 and the passivationfilm 13 formed over the surface of the semiconductor element 11.

[0073] According to the second embodiment, the following effects can beobtained in addition to the effects of the first embodiment (which areobtained by the first characteristic): when the temperature is varied tomelt the ball electrodes 16 in the process of mounting the semiconductordevice to the substrate, stresses are generated due to the difference inthermal expansion coefficient between the semiconductor device and thesubstrate. However, these stresses can be absorbed by the insulatingresin layer 17. As a result, the stresses are reduced, whereby theexternal electrode portion 14 a of the metal wiring 14 to which the ballelectrode 16 is connected can be prevented from being broken by thestresses.

[0074] According to the second embodiment, the portion of the metalwiring 14 other than the external electrode portion 14 a (i.e., thenon-electrode portion of the metal wiring 14) is covered with theinsulating film 15. This prevents wirings or electrodes of the substrateon which the semiconductor device is mounted from contacting thenon-electrode portions of the metal wirings 14 of the semiconductordevice. It is preferable that the exposed surface of the externalelectrode portion 14 a is flush with or higher than the surface of theinsulating film 15. In other words, it is preferable that the thicknessof the external electrode portion 14 a is equal to or greater than thatof the insulating film 15 on the insulating resin layer 17. The reasonfor this is as follows: if the external electrode portion 14 a isthinner than the insulating film 15 on the insulating resin layer 17,the ball electrode 16 cannot be mounted to the external electrodeportion 14 a (that is, the opening of the insulating film 15) without agap therebetween. As a result, sufficient junction between the ballelectrode 16 and the external electrode portion 14 a cannot be ensured.

[0075] Note that, in the second embodiment, the material of the metalwirings 14 is not specifically limited. For example, a material mainlycontaining Cu, Ti, W, Cr, Al or the like may be used. Alternatively,another conductive metal material may be used. However, forming themetal wiring 14 from a Cu-containing metal enables reduction inresistance of the metal wiring 14.

[0076] (Modification of Second Embodiment)

[0077] Hereinafter, a semiconductor device according to a modificationof the second embodiment will be described with reference to thefigures.

[0078]FIG. 6 is a cross-sectional view of the semiconductor deviceaccording to the modification of the second embodiment. Note that, inthe modification of the second embodiment, the same elements as those ofthe semiconductor device of the first embodiment in FIG. 1 or thesemiconductor device of the second embodiment in FIG. 4 are denoted withthe same reference numerals and characters, and description thereof ispartly omitted.

[0079] As shown in FIG. 6, electrodes 12 are formed on the surface of asemiconductor element 11. A passivation film 13 is formed over thesurface of the semiconductor element 11. The passivation film 13 has anopening on each electrode 12. An insulating resin layer 17 is formed onthe passivation film 13 excluding the regions near the electrodes 12.For example, the insulating resin layer 17 is formed from an epoxy resinhaving low elasticity. Metal wirings 14 are formed along the surface ofthe insulating resin layer 17. Each metal wiring 14 is electricallyconnected to a corresponding one of the electrodes 12. An insulatingfilm 15 is formed on the metal wirings 14, the insulating resin layer 17and the passivation film 13. The insulating film 15 has openings inorder to expose a portion of each metal wiring 14 which functions as anexternal electrode (hereinafter, referred to as “external electrodeportion 14 b”).

[0080] The modification of the second embodiment is different from thesecond embodiment in that each external electrode portion 14 b has amushroom-like projection over a corresponding one of the openings of theinsulating film 15. The mushroom-like projection is larger than theopening of the insulating film 15. Therefore, the exposed surface of theexternal electrode portion 14 b is higher than the surface of theinsulating film 15. As a result, a substantial thickness of a metalportion of the external electrode portion 14 b is larger than that ofthe external electrode portion 14 a of the second embodiment in FIG. 4.Therefore, the following effects can be obtained: when the externalelectrode portions 14 b and wiring electrodes of a substrate on whichthe semiconductor device is mounted are respectively connected to eachother by ball electrodes formed from solder, Sn contained in solder ofthe ball electrode diffuses into Cu contained in the metal wiring 14. Asa result, a Sn—Cu alloy layer having low strength grows in the thicknessdirection of the external electrode portion 14 b. As described above,however, the substantial thickness of the metal portion of the externalelectrode portion 14 b is larger than that of the external electrodeportion 14 a of the second embodiment in FIG. 4. It is therefore ensuredthat a greater part of the external electrode portion 14 b is leftunchanged into the Sn—Cu alloy in the thickness direction of theexternal electrode portion 14 b. When the temperature is varied in aprocess such as the process of mounting the semiconductor device ontothe substrate, stresses are generated due to the difference in thermalexpansion coefficient between the semiconductor device and thesubstrate. However, the above structure of the modification of thesecond embodiment can more reliably prevent disconnection of the metalwirings 14 even if such stresses are generated.

[0081] Note that, in the modification of the second embodiment, theexternal electrode portions 14 b may be bonded to the wiring electrodesof the substrate by solder without using the ball electrodes. In thiscase, the same effects as those described above can be obtained.

[0082] (Third Embodiment)

[0083] Hereinafter, a method for manufacturing a semiconductor deviceaccording to the third embodiment of the present invention will bedescribed with reference to the figures. Note that the manufacturingmethod of the third embodiment is a method for manufacturing thesemiconductor device of the first embodiment.

[0084]FIGS. 7A to 7E and FIGS. 8A, 8B illustrate the steps of the methodfor manufacturing a semiconductor device according to the thirdembodiment. FIGS. 7A and 8A are perspective views, and FIGS. 7B to 7Eand FIG. 8B are cross-sectional views. In the third embodiment, the sameelements as those of the semiconductor device of the first embodiment inFIGS. 1 and 2 are denoted with the same reference numerals andcharacters.

[0085] As shown in FIG. 7A, a semiconductor wafer 10 having a pluralityof semiconductor elements 11 formed thereon is prepared. Thesemiconductor wafer 10 has a plurality of chip regions R_(chip) definedby dicing lines 10 a. Each semiconductor element 11 is provided in acorresponding one of the plurality of chip regions R_(chip) of thesemiconductor wafer 10. The following description will be given for thesemiconductor element 11 provided in one of the plurality of chipregions R_(chip).

[0086] As shown in FIG. 7B, a passivation film 13 is formed over thesurface of the semiconductor element 11 having electrodes 12 formedthereon. For example, the passivation film 13 is formed from SiN. Thepassivation film 13 has an opening on each electrode 12. Metal wirings14 containing, e.g., Cu are then formed on the passivation film 13 so asto be electrically connected to the electrodes 12, respectively. Morespecifically, the metal wirings 14 are formed as follows: a titaniumtungsten (TiW) layer and a Cu layer are sequentially formed on thepassivation film 13 by a sputtering method. The TiW layer and the Culayer are then etched by using a mask which covers the regions where themetal wirings are to be formed (hereinafter, referred to as metal-wiringformation regions). The mask is formed from a photoresist material. Themetal wirings 14 having a desired pattern are thus formed. The resistmask is then removed.

[0087] As shown in FIG. 7C, an insulating film 15 is formed on thepassivation film 13 and the metal wirings 14. Openings are then formedin the insulating film 15 so as to expose a predetermined region of eachmetal wiring 14 (a region where an external electrode is to be formed;hereinafter, referred to as “external-electrode formation region”) by anetching method using a resist material (not shown). For example, theinsulating film 15 is a resin film having a thickness of 12 μm, and isformed from solder resist or the like. In the present embodiment, theinsulating film 15 is formed from a photosensitive material. Therefore,the opening pattern of the insulating film 15 is formed by using aphotolithography method capable of forming a fine pattern.

[0088] As shown in FIG. 7D, a metal film 18 is formed on the insulatingfilm 15 by, e.g., an electroplating method so as to completely fill theopenings of the insulating film 15. For example, the metal film 18 isformed from Ti and Cu. A resist mask 19 is then formed so as to coverthe regions of the metal film 18 on the openings of the insulating film15.

[0089] When the electroplating method is used in the step of FIG. 7D,wirings (not shown) formed in the dicing lines 10 a of the semiconductorwafer 10 in FIG. 7A serve as a power feeding point of the electroplatingmethod. These wirings are formed simultaneously with the metal wirings14 by e.g., a sputtering method.

[0090] As shown in FIG. 7E, the portion of the metal film 18 locatedoutside the resist mask 19 (i.e., the exposed portion of the metal film18) is removed by, e.g., a wet etching method. As a result,metal-material embedded portions 18A are formed by the metal film 18embedded in the openings of the insulating film 15. The resist mask 19is then removed. Note that the surface of the metal-material embeddedportions 18A is flush with or higher than the surface of the insulatingfilm 15. As a result, the total thickness of the metal-material embeddedportion 18A and the metal wiring 14 located thereunder is greater thanthe thickness of the portion of the metal wiring 14 other than theexternal electrode portion (i.e., the non-electrode portion of the metalwiring 14).

[0091] As shown in FIG. 8A, after the semiconductor elements 11 in therespective chip regions R_(chip) of the semiconductor wafer 10 aresubjected to the steps of FIGS. 7B to 7E, the semiconductor wafer 10 isdiced along the dicing lines 10 a into individual chips by a rotatingblade 20. In this step, the wirings serving as a power feeding point inthe electroplating method in the step of FIG. 7D are also cut in orderto discontinue current application through the wirings.

[0092] As shown in FIG. 8B, in order to electrically connect theelectrodes 12 formed on the surface of the semiconductor element 11 torespective wiring electrodes of a substrate (not shown) on which thesemiconductor element 11 is mounted, a ball electrode 16 is mounted oneach metal-material embedded portion 18A (i.e., the external electrodeportion of each metal wiring 14). For example, the ball electrodes 16are formed from solder or Cu. The ball electrodes 16 may be formed fromsolder by printing solder paste to the metal-material embedded portions18A by, e.g., a screen printing method and then reflowing the solderpaste.

[0093] As has been described above, according to the third embodiment,the metal wirings 14 are formed so as to be electrically connected tothe electrodes 12 of the semiconductor element 11, respectively. Theinsulating film 15 is then formed, and openings are formed in theinsulating film 15 so as to expose the external-electrode formationregions of the metal wirings 14. Thereafter, the metal-material embeddedportions 18A are embedded in the respective openings so that the surfaceof the metal-material embedded portions 18A is flush with or higher thanthe surface of the insulating film 15. Accordingly, the thickness of theexternal electrode portion of the metal wiring 14 (i.e., the totalthickness of the metal-material embedded portion 18A embedded in theopening of the insulating film 15 and the metal wiring 14 located underthe metal-material embedded portion 18A) is greater than the thicknessof the portion of the metal wiring 14 other than the external electrodeportion (i.e., the non-electrode portion of the metal wiring 14). As aresult, the same effects as those of the semiconductor device of thefirst embodiment can be obtained. More specifically, the metal-materialembedded portions 18A, that is, the external electrode portions, and thewiring electrodes of the substrate on which the semiconductor device ismounted are respectively connected to each other by the ball electrodes16. When the metal wirings 14 contain, e.g., Cu (which is a commonlyused metal wiring material), Sn contained in solder of the ballelectrode 16 diffuses into Cu contained in the metal-material embeddedportion 18A or the metal wiring 14, whereby a Sn—Cu alloy layer havinglow strength grows in the thickness direction of the external electrodeportion. However, since the thickness of the external electrode portionof the metal wiring 14 is greater than that of the non-electrode portionof the metal wiring 14, this Sn—Cu alloy layer can be prevented fromgrowing through the entire thickness of the external electrode portion.In other words, it is ensured that the thickness of the Sn—Cu alloylayer in the external electrode portion is smaller than the thickness ofthe external electrode portion. Since a part of the external electrodeportion is left unchanged into the Sn—Cu alloy layer, the strength ofthe metal wiring 14 can be maintained even if Cu is used as a metalwiring material. The semiconductor element 11, the resin film coveringthe surface of the semiconductor element 11, and the substrate havedifferent thermal expansion coefficients. Therefore, when thetemperature is varied in the process of hardening the resin filmcovering the surface of the semiconductor element 11 or the process ofmounting the semiconductor device onto the substrate, stresses aregenerated due to such a difference in thermal expansion coefficient.Even if such stresses are generated, however, the above structure of thethird embodiment can prevent the Sn—Cu alloy layer having low strengthfrom being broken and thus can prevent disconnection of the metalwirings 14.

[0094] According to the third embodiment, the portion of the metalwiring 14 other than the external electrode portion (i.e., thenon-electrode portion of the metal wiring 14) is covered with theinsulating film 15. This prevents wirings or electrodes of the substrateon which the semiconductor device is mounted from contacting thenon-electrode portions of the metal wirings 14 of the semiconductordevice. The surface of the metal-material embedded portion 18A, that is,the exposed surface of the external electrode portion, is flush with orhigher than the surface of the insulating film 15. In other words, thethickness of the external electrode portion (the total thickness of themetal-material embedded portion 18A and the metal wiring 14 locatedthereunder) is equal to or greater than that of the insulating film 15.Therefore, the following effects can be obtained: the ball electrode 16can be mounted to the external electrode portion (the metal-materialembedded portion 18A) without producing a gap therebetween. As a result,sufficient junction between the ball electrode 16 and the externalelectrode portion can be ensured.

[0095] In the third embodiment, the exposed surface of the externalelectrode portion (the surface of the metal-material embedded portion18A) may be higher than the surface of the insulating film. In thiscase, a substantial thickness of a metal portion of the externalelectrode portion is increased. Accordingly, the following effects canbe obtained: when Sn contained in solder of the ball electrode 16diffuses into Cu contained in the metal-material embedded portion 18A orthe metal wiring 14, a Sn—Cu alloy layer having low strength grows inthe thickness direction of the external electrode portion. As describedabove, however, since the substantial thickness of the metal portion ofthe external electrode portion is increased, it is ensured that agreater part of the external electrode portion is left unchanged intothe Sn—Cu alloy in the thickness direction of the external electrodeportion. When the temperature is varied in a process such as the processof mounting the semiconductor device onto the substrate, stresses aregenerated due to the difference in thermal expansion coefficient betweenthe semiconductor device and the substrate. However, the above structureof the third embodiment can more reliably prevent disconnection of themetal wirings 14 even if such stresses are generated. Note that, whenthe exposed surface of the external electrode portion (the surface ofthe metal-material embedded portion 18A) is higher than the surface ofthe insulating film 15, the external electrode portions may be bonded tothe wiring electrodes of the substrate by solder without using the ballelectrodes 16. In this case, the same effects as those described abovecan be obtained.

[0096] Note that, in the third embodiment, the material of the metalwirings 14 is not specifically limited. For example, a material mainlycontaining Cu, Ti, W, Cr, Al or the like may be used. Alternatively,another conductive metal material may be used. However, forming themetal wiring 14 from a Cu-containing metal enables reduction inresistance of the metal wiring 14.

[0097] In the third embodiment, the TiW layer and the Cu layer forforming the metal wirings 14 are sequentially formed by a sputteringmethod. However, the TiW layer and the Cu layer may alternatively beformed by a plating method, a screen printing method or the like.

[0098] In the third embodiment, the insulating film 15 is formed from aphotosensitive material, and the opening pattern of the insulating film15 is formed by a photolithography method capable of forming a finepattern. However, the insulating film 15 may alternatively be formedfrom a non-photosensitive material, and the opening pattern of theinsulating film 15 may alternatively be formed by a screen printingmethod or the like.

[0099] In the third embodiment, the metal film 18, that is, themetal-material embedded portions 18A, are formed from Ti and Cu.However, the metal film 18, that is, the metal-material embeddedportions 18A, may alternatively be formed from a material mainlycontaining TiW, Cr, nickel (Ni), gold (Au) or the like. If the metalfilm 18 is formed by an electroplating method, the metal film 18, thatis, the metal-material embedded portions 18A, may be formed from amaterial mainly containing Au, silver (Ag), palladium (Pd), lead (Pb),Ni or the like.

[0100] In the third embodiment, the surface of the metal-materialembedded portions 18A is flush with or higher than the surface of theinsulating film 15. In other words, the thickness of the externalelectrode portion (i.e., the total thickness of the metal-materialembedded portion 18A and the metal wiring 14 located thereunder) isequal to or greater than the thickness of the insulating film 15. Morespecifically, the thickness of the external electrode portion ispreferably in the range of 10 μm to 20 μm. If the thickness of theexternal electrode portion exceeds 20 μm, greater pattern deformationwould be generated in the process of forming the metal-material embeddedportions by a wet etching method.

[0101] In the third embodiment, the metal film 18 is formed by anelectroplating method. However, the metal film 18 may alternatively beformed by an electroless plating method, a screen printing method or thelike.

[0102] In the third embodiment, it is preferable to form an insulatingresin layer on the passivation film 13 excluding the regions near theelectrodes 12 before the metal wirings 14 are formed, and to form themetal wirings 14 along the surface of the insulating resin layer. Inthis case, the following effects can be obtained: when the temperatureis varied to melt the ball electrodes 16 in the process of mounting thesemiconductor device to the substrate, stresses are generated due to thedifference in thermal expansion coefficient between the semiconductordevice and the substrate. However, these stresses can be absorbed by theinsulating resin layer. As a result, the stresses are reduced, wherebythe external electrode portion of the metal wiring 14 to which the ballelectrode 16 is connected can be prevented from being broken by thestresses.

[0103] (Fourth Embodiment)

[0104] Hereinafter, a method for manufacturing a semiconductor deviceaccording to the fourth embodiment of the present invention will bedescribed with reference to the figures. Note that the manufacturingmethod of the fourth embodiment is a method for manufacturing thesemiconductor device of the modification of the second embodiment.

[0105]FIGS. 9A to 9D and FIGS. 10A to 10C illustrate the steps of themethod for manufacturing a semiconductor device according to the fourthembodiment. FIGS. 9A and 10B are perspective views, and FIGS. 9B to 9Dand FIGS. 10A, 10C are cross-sectional views. In the fourth embodiment,the same elements as those of the third embodiment in FIGS. 7A to 7E andFIGS. 8A, 8B are denoted with the same reference numerals andcharacters, and description thereof is partly omitted.

[0106] As shown in FIG. 9A, a semiconductor wafer 10 having a pluralityof semiconductor elements 11 formed thereon is prepared. Thesemiconductor wafer 10 has a plurality of chip regions R_(chip) definedby dicing lines 10 a. Each semiconductor element 11 is provided in acorresponding one of the plurality of chip regions R_(chip) of thesemiconductor wafer 10. The following description will be given for thesemiconductor element 11 provided in one of the plurality of chipregions R_(chip).

[0107] As shown in FIG. 9B, a passivation film 13 is formed over thesurface of the semiconductor element 11 having electrodes 12 formedthereon. For example, the passivation film 13 is formed from SiN. Thepassivation film 13 has an opening on each electrode 12. An insulatingresin layer 17 is then formed on the passivation film 13 excluding theregions near the electrodes 12. For example, the insulating resin layer17 is formed from an epoxy resin having low elasticity. In the presentembodiment, the low-elasticity resin material of the insulating resinlayer 17 is a photosensitive material. The insulating resin layer 17having a desired pattern is formed by patterning a film of thephotosensitive material by a photolithography method.

[0108] As shown in FIG. 9C, metal wirings 14 are formed along thesurface of the insulating resin layer 17 so as to be electricallyconnected to the electrodes 12, respectively. For example, the metalwirings 14 have a thickness of 5 μm and are formed from Cu. Morespecifically, a Cu layer is formed on the insulating resin layer 17 by asputtering method.

[0109] As shown in FIG. 9D, an insulating film 15 is formed on thepassivation film 13, the insulating resin layer 17 and the metal wirings14. Openings are then formed in the insulating film 15 so as to expose apredetermined region (external-electrode formation region) of each metalwiring 14. For example, the insulating film 15 is a resin film formedfrom solder resist or the like.

[0110] As shown in FIG. 10A, metal-material embedded portions 21 areformed in the openings of the insulating film 15 so as to be connectedto the metal wirings 14, respectively. The thickness of themetal-material embedded portions 21 is greater than that of theinsulating film 15. More specifically, the metal-material embeddedportions 21 are formed from Cu, and formed by an electroless platingmethod. As a result, the top portions of the metal-material embeddedportions 21 projecting from the surface of the insulating film 15 serveas projecting electrodes. The thickness of the external electrodeportion (the total thickness of the metal-material embedded portion 21and the metal wiring 14 located thereunder) is larger than that of theportion of the metal wiring 14 other than the external electrode portion(the non-electrode portion of the metal wiring 14).

[0111] As shown in FIG. 10B, after the semiconductor elements 11 in therespective chip regions R_(chip) of the semiconductor wafer 10 aresubjected to the steps of FIGS. 9B to 9D and FIG. 10A, the semiconductorwafer 10 is diced along the dicing lines 10 a by a rotating blade 20. Asa result, individual chips of the semiconductor elements 11 are obtainedas shown in FIG. 10C.

[0112] As has been described above, according to the fourth embodiment,the following effects can be obtained in addition to the effects of thethird embodiment: when the temperature is varied to melt the ballelectrodes in the process of mounting the semiconductor device to thesubstrate (the ball electrodes are mounted to the external electrodeportions of the metal wirings 14, and each external electrode portion isformed by the metal-material embedded portion 21 and the metal wiring 14located thereunder), stresses are generated due to the difference inthermal expansion coefficient between the semiconductor device and thesubstrate. However, these stresses can be absorbed by the insulatingresin layer 17. As a result, the stresses are reduced, whereby theexternal electrode portion of the metal wiring 14 to which the ballelectrode is connected can be prevented from being broken by thestresses.

[0113] According to the fourth embodiment, the portion of the metalwiring 14 other than the external electrode portion (i.e., thenon-electrode portion of the metal wiring 14) is covered with theinsulating film 15. This prevents wirings or electrodes of the substrateon which the semiconductor device is mounted from contacting thenon-electrode portions of the metal wirings 14 of the semiconductordevice. The surface of the metal-material embedded portion 21, that is,the exposed surface of the external electrode portion, is higher thanthe surface of the insulating film 15. In other words, the thickness ofthe external electrode portion is greater than that of the insulatingfilm 15. Therefore, the following effects can be obtained: the ballelectrode can be mounted to the external electrode portion (themetal-material embedded portion 21) without producing a gaptherebetween. As a result, sufficient junction between the ballelectrode and the external electrode portion can be ensured. Moreover,when Sn contained in solder of the ball electrode diffuses into Cucontained in the metal-material embedded portion 21 or the metal wiring14, a Sn—Cu alloy layer having low strength grows in the thicknessdirection of the external electrode portion. According to the abovestructure of the fourth embodiment, however, it is ensured that agreater part of the external electrode portion is left unchanged intothe Sn—Cu alloy in the thickness direction of the external electrodeportion. When the temperature is varied in a process such as the processof mounting the semiconductor device onto the substrate, stresses aregenerated due to the difference in thermal expansion coefficient betweenthe semiconductor device and the substrate. However, the above structureof the fourth embodiment can more reliably prevent disconnection of themetal wirings 14 even if such stresses are generated. Note that, whenthe exposed surface of the external electrode portion (the surface ofthe metal-material embedded portion 21) is higher than the surface ofthe insulating film 15, the external electrode portions may be bonded tothe wiring electrodes of the substrate by solder without using the ballelectrodes. In this case, the same effects as those described above canbe obtained.

[0114] Note that, in the fourth embodiment, the material of the metalwirings 14 is not specifically limited. For example, a material mainlycontaining Cu, Ti, W, Cr, Al or the like may be used. Alternatively,another conductive metal material may be used.

[0115] However, forming the metal wiring 14 from a Cu-containing metalenables reduction in resistance of the metal wiring 14.

[0116] In the fourth embodiment, the Cu layer for forming the metalwirings 14 is formed by a sputtering method. However, the Cu layer mayalternatively be formed by a plating method, a screen printing method orthe like.

[0117] In the fourth embodiment, the metal-material embedded portions 21are formed from Cu. However, another metal material (e.g., a metalmaterial used in another embodiment) may alternatively be used.

[0118] In the fourth embodiment, the metal-material embedded portions 21are formed by an electroless plating method. However, the metal-materialembedded portions 21 may alternatively be formed by, e.g., anelectroplating method.

[0119] In the fourth embodiment, the surface of the metal-materialembedded portions 21 is higher than the surface of the insulating film15. However, the surface of the metal-material embedded portions 21 mayalternatively be flush with the surface of the insulating film 15. Inthis case, a semiconductor device having the same structure as that ofthe semiconductor device of the second embodiment is obtained. Note thatthe thickness of the external electrode portion (the total thickness ofthe metal-material embedded portion 21 and the metal wiring 14 locatedthereunder) is preferably in the range of 10 μm to 20 μm.

[0120] (Fifth Embodiment)

[0121] Hereinafter, a method for manufacturing a semiconductor deviceaccording to the fifth embodiment of the present invention will bedescribed with reference to the figures. Note that, like the thirdembodiment, the manufacturing method of the fifth embodiment is a methodfor manufacturing the semiconductor device of the first embodiment.

[0122]FIGS. 11A to 11E and FIGS. 12A to 12C illustrate the steps of themethod for manufacturing a semiconductor device according to the fifthembodiment. FIGS. 11A and 12B are perspective views, and FIGS. 11B to11E and FIGS. 12A, 12C are cross-sectional views. In the fifthembodiment, the same elements as those of the semiconductor device ofthe third embodiment in FIGS. 7A to 7E and FIGS. 8A, 8B are denoted withthe same reference numerals and characters.

[0123] As shown in FIG. 11A, a semiconductor wafer 10 having a pluralityof semiconductor elements 11 formed thereon is prepared. Thesemiconductor wafer 10 has a plurality of chip regions R_(chip) definedby dicing lines 10 a. Each semiconductor element 11 is provided in acorresponding one of the plurality of chip regions R_(chip) of thesemiconductor wafer 10. The following description will be given for thesemiconductor element 11 provided in one of the plurality of chipregions R_(chip).

[0124] As shown in FIG. 11B, a passivation film 13 is formed over thesurface of the semiconductor element 11 having electrodes 12 formedthereon. For example, the passivation film 13 is formed from SiN. Thepassivation film 13 has an opening on each electrode 12. Metal wirings14 containing, e.g., Cu are then formed on the passivation film 13 so asto be electrically connected to the electrodes 12, respectively. Morespecifically, the metal wirings 14 are formed as follows: a TiW layerand a Cu layer are sequentially formed on the passivation film 13 by asputtering method. The TiW layer and the Cu layer are then etched byusing a mask which covers the regions where the metal wirings are to beformed (i.e., the metal-wiring formation regions). The mask is formedfrom a photoresist material. The metal wirings 14 having a desiredpattern are thus formed. The resist mask is then removed.

[0125] As shown in FIG. 11C, an insulating film 15 is formed on thepassivation film 13 and the metal wirings 14. Openings are then formedin the insulating film 15 so as to expose a predetermined region of eachmetal wiring 14 (a region where an external electrode is to be formed,i.e., an external-electrode formation region). For example, theinsulating film 15 is a resin film having a thickness of 12 μm, and isformed from solder resist or the like. In the present embodiment, theinsulating film 15 is formed from a photosensitive material. Therefore,the opening pattern of the insulating film 15 is formed by using aphotolithography method capable of forming a fine pattern.

[0126] As shown in FIG. 11D, a first metal film 22 containing, e.g., Cuis formed on the insulating film 15 so that each opening of theinsulating film 15 is partially filled with the first metal film 22.More specifically, the first metal film 22 is formed by sequentiallyforming a TiW layer and a Cu layer on the insulating film 15 by asputtering method. Thereafter, a resist mask 23 is formed so as to coverthe region of the insulating film 15 located outside the openings. Inother words, the resist mask 23 is formed so as to expose the openingsof the insulating film 15.

[0127] As shown in FIG. 11E, a second metal film 24 is formed on theexposed regions of the first metal film 22 by, e.g., an electroplatingmethod so as to completely fill the openings of the insulating film 15.The exposed regions of the first metal film 22 are the regions of thefirst metal film 22 located within the openings of the insulating film15 and surrounded by the resist mask 23. For example, the second metalfilm 24 is formed from Cu.

[0128] As shown in FIG. 12A, the resist mask 23 is removed, and theportion of the first metal film 22 located outside the openings of theinsulating film 15 are removed by an etching method. As a result,metal-material embedded portions 25 are formed by the first and secondmetal films 22, 24 embedded in the openings of the insulating film 15.Note that the surface of the metal-material embedded portions 25 isflush with or higher than the surface of the insulating film 15. Inother words, the thickness of the external electrode portion (the totalthickness of the metal-material embedded portion 25 and the metal wiring14 located thereunder) is equal to or greater than that of theinsulating film 15. As a result, the thickness of the external electrodeportion is greater than the thickness of the portion of the metal wiring14 other than the external electrode portion (i.e., the non-electrodeportion of the metal wiring 14).

[0129] As shown in FIG. 12B, after the semiconductor elements 11 in therespective chip regions R_(chip) of the semiconductor wafer 10 aresubjected to the steps of FIGS. 11B to 11E and FIG. 12A, thesemiconductor wafer 10 is diced along the dicing lines 10 a by arotating blade 20. As a result, individual chips of the semiconductorelements 11 are obtained as shown in FIG. 12C.

[0130] As has been described above, according to the fifth embodiment,the metal wirings 14 are formed so as to be electrically connected tothe electrodes 12 of the semiconductor element 11, respectively. Theinsulating film 15 is then formed, and openings are formed in theinsulating film 15 so as to expose the external-electrode formationregions of the metal wirings 14. Thereafter, the metal-material embeddedportions 25 are embedded in the respective openings so that the surfaceof the metal-material embedded portions 25 is flush with or higher thanthe surface of the insulating film 15. Accordingly, the thickness of theexternal electrode portion (i.e., the total thickness of themetal-material embedded portion 25 embedded in the opening of theinsulating film 15 and the metal wiring 14 located under themetal-material embedded portion 25) is greater than the thickness of theportion of the metal wiring 14 other than the external electrode portion(i.e., the non-electrode portion of the metal wiring 14). As a result,the same effects as those of the manufacturing method of the thirdembodiment can be obtained.

[0131] According to the fifth embodiment, the portion of the metalwiring 14 other than the external electrode portion (i.e., thenon-electrode portion of the metal wiring 14) is covered with theinsulating film 15. This prevents wirings or electrodes of a substrateon which the semiconductor device is mounted from contacting thenon-electrode portions of the metal wirings 14 of the semiconductordevice. The surface of the metal-material embedded portion 25, that is,the exposed surface of the external electrode portion, is flush with orhigher than the surface of the insulating film 15. In other words, thethickness of the external electrode portion (the total thickness of themetal-material embedded portion 25 and the metal wiring 14 locatedthereunder) is equal to or greater than that of the insulating film 15.Therefore, the following effects can be obtained: a ball electrode canbe mounted to the external electrode portion (the metal-materialembedded portion 25) without producing a gap therebetween. As a result,sufficient junction between the ball electrode and the externalelectrode portion can be ensured.

[0132] In the fifth embodiment, the exposed surface of the externalelectrode portion (the surface of the metal-material embedded portion25) may be higher than the surface of the insulating film. In this case,a substantial thickness of a metal portion of the external electrodeportion is increased. Accordingly, the following effects can beobtained: when Sn contained in solder of the ball electrode diffusesinto Cu contained in the metal-material embedded portion 25 or the metalwiring 14, a Sn—Cu alloy layer having low strength grows in thethickness direction of the external electrode portion. As describedabove, however, since the substantial thickness of the metal portion ofthe external electrode portion is increased, it is ensured that agreater part of the external electrode portion is left unchanged intothe Sn—Cu alloy in the thickness direction of the external electrodeportion. When the temperature is varied in a process such as the processof mounting the semiconductor device onto the substrate, stresses aregenerated due to the difference in thermal expansion coefficient betweenthe semiconductor device and the substrate. However, the above structureof the fifth embodiment can more reliably prevent disconnection of themetal wirings 14 even if such stresses are generated. Note that, whenthe exposed surface of the external electrode portion (the surface ofthe metal-material embedded portion 25) is higher than the surface ofthe insulating film 15, the external electrode portions may be bonded tothe wiring electrodes of the substrate by solder without using the ballelectrodes. In this case, the same effects as those described above canbe obtained.

[0133] Note that, in the fifth embodiment, the material of the metalwirings 14 is not specifically limited. For example, a material mainlycontaining Cu, Ti, W, Cr, Al or the like may be used. Alternatively,another conductive metal material may be used. However, forming themetal wiring 14 from a Cu-containing metal enables reduction inresistance of the metal wiring 14.

[0134] In the fifth embodiment, the TiW layer and the Cu layer forforming the metal wirings 14 are sequentially formed by a sputteringmethod. However, the TiW layer and the Cu layer may alternatively beformed by a plating method, a screen printing method or the like.

[0135] In the fifth embodiment, the insulating film 15 is formed from aphotosensitive material, and the opening pattern of the insulating film15 is formed by a photolithography method capable of forming a finepattern. However, the insulating film 15 may alternatively be formedfrom a non-photosensitive material, and the opening pattern of theinsulating film 15 may alternatively be formed by a screen printingmethod or the like.

[0136] In the fifth embodiment, the material of the first metal film 22is not specifically limited. For example, a material mainly containingCu, Ti, W, Cr, Al or the like may be used. Alternatively, anotherconductive metal material may be used.

[0137] In the fifth embodiment, the TiW layer and the Cu layer forforming the first metal film 22 are sequentially formed by a sputteringmethod. However, the TiW layer and the Cu layer may alternatively beformed by a plating method, a screen printing method or the like.

[0138] In the fifth embodiment, the second metal film 24 is formed fromCu. However, the second metal film 24 may alternatively be formed from amaterial mainly containing Ni, Ag, Au, Sn, Pd or the like.

[0139] In the fifth embodiment, the metal-material embedded portion 25having its top portion larger than the opening of the insulating film 15may be formed by a screen printing method or the like so that the topportion of the metal-material embedded portion 25 projecting from thesurface of the insulating film 15 serves as a mushroom-like projectingelectrode. In this case, a semiconductor device having the samestructure as that of the semiconductor device of the modification of thefirst embodiment is formed. In the fifth embodiment, the second metalfilm 24 is formed by an electroplating method. However, the second metalfilm 24 may alternatively be formed by an electroless plating method, ascreen printing method or the like.

[0140] In the fifth embodiment, the surface of the metal-materialembedded portions 25 is flush with or higher than the surface of theinsulating film 15. In other words, the thickness of the externalelectrode portion (i.e., the total thickness of the metal-materialembedded portion 25 and the metal wiring 14 located thereunder) is equalto or greater than the thickness of the insulating film 15. Morespecifically, the thickness of the external electrode portion ispreferably in the range of 10 μm to 20 μm. If the thickness of theexternal electrode portion exceeds 20 μm, it is difficult to form theresist mask 23 having a sufficient thickness (see FIG. 11D) near theopenings (i.e., stepped portions) of the insulating film 15.

[0141] In the fifth embodiment, it is preferable to form an insulatingresin layer on the passivation film 13 excluding the regions near theelectrodes 12 before the metal wirings 14 are formed, and to form themetal wirings 14 along the surface of the insulating resin layer. Inthis case, the following effects can be obtained: when the temperatureis varied to melt the ball electrodes in the process of mounting thesemiconductor device to the substrate, stresses are generated due to thedifference in thermal expansion coefficient between the semiconductordevice and the substrate. However, these stresses can be absorbed by theinsulating resin layer. As a result, the stresses are reduced, wherebythe external electrode portion of the metal wiring 14 to which the ballelectrode is connected can be prevented from being broken by thestresses.

[0142] (Sixth Embodiment)

[0143] Hereinafter, a method for manufacturing a semiconductor deviceaccording to the sixth embodiment of the present invention will bedescribed with reference to the figures.

[0144]FIGS. 13A to 13D and FIGS. 14A, 14B illustrate the steps of themethod for manufacturing a semiconductor device according to the sixthembodiment. FIGS. 13A and 14A are perspective views, and FIGS. 13B to13D and FIG. 14B are cross-sectional views. In the sixth embodiment, thesame elements as those of the third embodiment in FIGS. 7A to 7E andFIGS. 8A, 8B are denoted with the same reference numerals andcharacters.

[0145] As shown in FIG. 13A, a semiconductor wafer 10 having a pluralityof semiconductor elements 11 formed thereon is prepared. Thesemiconductor wafer 10 has a plurality of chip regions R_(chip) definedby dicing lines 10 a. Each semiconductor element 11 is provided in acorresponding one of the plurality of chip regions R_(chip) of thesemiconductor wafer 10. The following description will be given for thesemiconductor element 11 provided in one of the plurality of chipregions R_(chip).

[0146] As shown in FIG. 13B, a passivation film 13 is formed over thesurface of the semiconductor element 11 having electrodes 12 formedthereon. For example, the passivation film 13 is formed from SiN. Thepassivation film 13 has an opening on each electrode 12. Metal wirings14 containing, e.g., Cu are then formed on the passivation film 13 so asto be electrically connected to the electrodes 12, respectively. Morespecifically, the metal wirings 14 are formed as follows: a TiW layerand a Cu layer are sequentially formed on the passivation film 13 by asputtering method. The TiW layer and the Cu layer are then etched byusing a mask which covers the regions where the metal wirings are to beformed (i.e., the metal-wiring formation regions). The mask is formedfrom a photoresist material. The metal wirings 14 having a desiredpattern are thus formed. The resist mask is then removed.

[0147] As shown in FIG. 13C, projecting electrodes 26 having a thicknessof about 20 μm are formed as follows: conductive resin paste is appliedwith a desired pattern to a predetermined region of each metal wiring 14(a region where an external electrode is to be formed, i.e., anexternal-electrode formation region) by a screen printing method or thelike. For example, powdered Ag added to a thermosetting epoxy resin isused as the resin paste.

[0148] As shown in FIG. 13D, an insulating film 15 having a thickness ofabout 15 μm is formed on the passivation film 13 and the metal wirings14 (i.e., over the surface of the semiconductor wafer 10). As a result,the top portions of the projecting electrodes 26 are exposed from thesurface of the insulating film 15. For example, the insulating film 15is a resin film formed from solder resist or the like, and is formed bya spin coating method or the like.

[0149] Note that, in the present embodiment, the top portions of theprojecting electrodes 26 may be cleaned by etching the surface of thesemiconductor wafer 10 by a dry etching method using oxygen gas afterthe insulating film 15 is formed. This improves conductivity between theprojecting electrodes 26 of the semiconductor device and the wiringelectrodes of a substrate on which the semiconductor device is mounted.

[0150] As shown in FIG. 14A, after the semiconductor elements 11 in therespective chip regions R_(chip) of the semiconductor wafer 10 aresubjected to the steps of FIGS. 13B to 13D, the semiconductor wafer 10is diced along the dicing lines 10 a by a rotating blade 20. As aresult, individual chips of the semiconductor elements 11 are obtainedas shown in FIG. 14B.

[0151] As has been described above, according to the sixth embodiment,the metal wirings 14 are formed so as to be electrically connected tothe electrodes 12 of the semiconductor element 11, respectively.Thereafter, the projecting electrodes 26 are respectively formed on theexternal-electrode formation regions of the metal wirings 14, and theinsulating film 15 is then formed so as to expose the top portions ofthe projecting electrodes 26. Accordingly, the thickness of the externalelectrode portion (i.e., the total thickness of the projecting electrode26 and the metal wiring 14 located thereunder) is greater than thethickness of the portion of the metal wiring 14 other than the externalelectrode portion (i.e., the non-electrode portion of the metal wiring14). As a result, the same effects as those of the semiconductor deviceof the third embodiment can be obtained.

[0152] According to the sixth embodiment, the portion of the metalwiring 14 other than the external electrode portion (i.e., thenon-electrode portion of the metal wiring 14) is covered with theinsulating film 15. This prevents wirings or electrodes of the substrateon which the semiconductor device is mounted from contacting thenon-electrode portions of the metal wirings 14 of the semiconductordevice. The surface of the projecting electrode 26, that is, the exposedsurface of the external electrode portion, is higher than the surface ofthe insulating film 15. In other words, the thickness of the externalelectrode portion is greater than that of the insulating film 15.Therefore, the following effects can be obtained: a ball electrode canbe mounted to the external electrode portion (the projecting electrode26) without producing a gap therebetween. As a result, sufficientjunction between the ball electrode and the external electrode portioncan be ensured. Moreover, when Sn contained in solder of the ballelectrode diffuses into Cu contained in the projecting electrode 26 orthe metal wiring 14, a Sn—Cu alloy layer having low strength grows inthe thickness direction of the external electrode portion. According tothe above structure of the sixth embodiment, however, it is ensured thata greater part of the external electrode portion is left unchanged intothe Sn—Cu alloy in the thickness direction of the external electrodeportion. When the temperature is varied in a process such as the processof mounting the semiconductor device onto the substrate, stresses aregenerated due to the difference in thermal expansion coefficient betweenthe semiconductor device and the substrate. However, the above structureof the sixth embodiment can more reliably prevent disconnection of themetal wirings 14 even if such stresses are generated. Note that, whenthe exposed surface of the external electrode portion (the surface ofthe projecting electrode 26) is higher than the surface of theinsulating film 15, the external electrode portions may be bonded to thewiring electrodes of the substrate by solder without using the ballelectrodes. In this case, the same effects as those described above canbe obtained.

[0153] Note that, in the sixth embodiment, the material of the metalwirings 14 is not specifically limited. For example, a material mainlycontaining Cu, Ti, W, Cr, Al or the like may be used. Alternatively,another conductive metal material may be used. However, forming themetal wiring 14 from a Cu-containing metal enables reduction inresistance of the metal wiring 14.

[0154] In the sixth embodiment, the TiW layer and the Cu layer forforming the metal wirings 14 are sequentially formed by a sputteringmethod. However, the TiW layer and the Cu layer may alternatively beformed by a plating method, a screen printing method or the like.

[0155] In the sixth embodiment, a conductive component of the resinpaste for forming the projecting electrodes 26 is not specificallylimited. For example, Ni, Cu, Au, Ag, Sn, Pd or the like may be used asthe conductive component.

[0156] In the sixth embodiment, the insulating film 15 is formed by aspin coating method. However, the insulating film 15 may alternativelybe formed by a curtain coating method.

[0157] In the sixth embodiment, it is preferable to form an insulatingresin layer on the passivation film 13 excluding the regions near theelectrodes 12 before the metal wirings 14 are formed, and to form themetal wirings 14 along the surface of the insulating resin layer. Inthis case, the following effects can be obtained: when the temperatureis varied to melt the ball electrodes in the process of mounting thesemiconductor device to the substrate, stresses are generated due to thedifference in thermal expansion coefficient between the semiconductordevice and the substrate. However, these stresses can be absorbed by theinsulating resin layer. As a result, the stresses are reduced, wherebythe external electrode portion of the metal wiring 14 to which the ballelectrode is connected can be prevented from being broken by thestresses.

What is claimed is:
 1. A semiconductor device, comprising: asemiconductor element having an electrode formed on a surface thereof,and a metal wiring formed on the surface of the semiconductor elementand electrically connected to the electrode, wherein the metal wiringhas an external electrode portion functioning as an external electrode,and a thickness of the external electrode portion is greater than thatof a non-electrode portion of the metal wiring, i.e., a portion of themetal wiring other than the external electrode portion.
 2. Thesemiconductor device according to claim 1, further comprising: aninsulating film formed on the metal wiring and the surface of thesemiconductor element, and having an opening exposing the externalelectrode portion, and an exposed surface of the external electrodeportion is flush with or higher than a surface of the insulating film.3. The semiconductor device according to claim 1, wherein the metalwiring is formed from a metal containing copper.
 4. The semiconductordevice according to claim 1, further comprising: an insulating resinlayer formed between the surface of the semiconductor element and themetal wiring, and the metal wiring is formed along a surface of theinsulating resin layer.
 5. The semiconductor device according to claim1, wherein the thickness of the external electrode portion is in a rangeof 10 μm to 20 μm.
 6. A method for manufacturing a semiconductor device,comprising: a first step of forming, on a surface of a semiconductorelement having an electrode formed thereon, a metal wiring electricallyconnected to the electrode; a second step of forming, on the surface ofthe semiconductor element and the metal wiring, an insulating filmhaving an opening which exposes a region of the metal wiring layer wherean external electrode is to be formed; and a third step of forming ametal-material embedded portion in the opening so that a surface of themetal-material embedded portion is flush with or higher than a surfaceof the insulating film.
 7. The method according to claim 6, furthercomprising before the first step the step of: forming an insulatingresin film on the surface of the semiconductor element except theelectrode, wherein the first step includes the step of forming the metalwiring along a surface of the insulating resin layer.
 8. The methodaccording to claim 6, wherein the third step includes the step offorming a metal film on the insulating film so as to completely fill theopening, forming a mask pattern which covers a region of the metal filmlocated on the opening, removing a region of the metal film locatedoutside the mask pattern, and removing the mask pattern.
 9. The methodaccording to claim 6, wherein the third step includes the step offorming a first metal film on the surface of the insulating film so asto partially fill the opening, forming a mask pattern which covers aregion of the first metal film located outside the opening, forming asecond metal film on a region of the first metal film located in theopening, and removing the mask pattern and the region of the first metalfilm located outside the opening.
 10. The method according to claim 6,wherein the semiconductor element is provided in each of a plurality ofchip regions of a semiconductor wafer, which are defined by a dicingline, the method further comprising after the third step the step of:dicing the semiconductor wafer along the dicing line by a rotating bladein order to divide the semiconductor wafer into chips of thesemiconductor elements.
 11. A method for manufacturing a semiconductordevice, comprising: a first step of forming, on a surface of asemiconductor element having an electrode formed thereon, a metal wiringelectrically connected to the electrode; a second step of forming aprojecting electrode on a region of the metal wiring where an externalelectrode is to be formed; and a third step of forming an insulatingfilm on the surface of the semiconductor element and the metal wiring soas to expose at least a top portion of the projecting electrode.
 12. Themethod according to claim 11, further comprising before the first stepthe step of: forming an insulating resin film on the surface of thesemiconductor element except the electrode, wherein the first stepincludes the step of forming the metal wiring along a surface of theinsulating resin layer.
 13. The method according to claim 11, whereinthe semiconductor element is provided in each of a plurality of chipregions of a semiconductor wafer, which are defined by a dicing line,the method further comprising after the third step the step of: dicingthe semiconductor wafer along the dicing line by a rotating blade inorder to divide the semiconductor wafer into chips of the semiconductorelements.